This invention relates to vehicle brake systems and, more particularly, to a center tracking roller and cam arrangement for maintaining vehicle wheel brake components in a preferred alignment during braking applications.
Heavy duty vehicles such as trucks typically include drum brake assemblies. Although drum brake assemblies are well known, those skilled in the art are constantly trying to improve performance characteristics. One problem encountered in drum brake assemblies is the occurrence of undesirable noise or brake chatter. Brake chatter is a phenomena caused by the relatively large forces imposed upon the various components of a drum brake assembly. If the components of a drum brake assembly do not fit together with relatively tight tolerances, they tend to rattle undesirably and create noise. Although attempts have been made at providing closer-fitting and quieter components, no effective and economically feasible arrangements have been developed prior to this invention.
In one well known type of brake assembly, an S-cam is rotated to cam opposed rollers between actuated and non-actuated positions. Brake shoes move with the rollers to actuate the brakes. It is most important that the cam/roller/brake shoe interface provide a tight fit. Clearance between the cam, rollers and brake shoes results in relative side-to-side motion, sliding, and brake chatter.
This invention provides a vehicle wheel drum brake assembly having a center tracking roller and cam arrangement that operates to maintain the brake shoes, the cam and the roller in an appropriate alignment by providing a zero clearance joint between the brake shoes, cam and roller. This invention further provides a more reliable cam actuated drum brake assembly.